Generally, a forced convection-type heater has been widely used in heating a relatively voluminous indoor space. In the case such a heater runs for a long time, the indoor air becomes impure and dry, and this causes indoor workers to have respiratory trouble. Therefore, use of a humidifier is essential to use of the heater.
One example of a humidifier for use in such a heater is disclosed in Japanese Laid-Open Publn. No. SHO 62-245050 of Oct. 26, 1987. The humidifier which is disclosed in that publication comprises a humidifying water tank enclosing a burner with an air stream passage defined between the tank and burner. The burner heats the air stream blown by a blower, and the humidifying water, to generate steam. The heated air stream carrying the steam is blown into the indoor space by a conventional blower.
However, the heater equipped with such humidifier results in a large size for the equipment.
FIG. 1 is a schematic view illustrating another heater having a humidifier of the prior art, which the present invention directly improves. In FIG. 1, a humidifying water tank 32 with its top open is mounted on the burned gas distribution chamber 30 formed at the end portion of the burner 20. The humidifying water is heated by the heat produced by burning gas in the chamber 30, and steam is thereby generated. The chamber 30 is also provided with a plurality of pipes 35 which are arranged above the burner 20 and directed to the exhaust gas collection tank 50. The generated steam is introduced into the air stream, which is heated while passing the burner 20 and pipes 35 in turn, and the humidified and heated air is blown into the indoor space.
Although the heater as described hereinabove in regard to FIG. 1 is more excellent in the thermal efficiency than the heater disclosed in Japanese Laid-Open Publn. No. SHO 62-245050, the humidifying effect is still not sufficient. Furthermore, when a sudden impact is given to the heater, humidifying water may be spilled from the open top of the water tank and the parts of the heater are thereby damaged.